Denial of Service Vulnerability in Multer Node.js Middleware
CVE-2026-3520

8.7HIGH

Key Information:

Vendor

Expressjs

Status
Multer
Vendor
CVE Published:
4 March 2026

What is CVE-2026-3520?

Multer, a middleware for handling multipart/form-data in Node.js, has a vulnerability that allows attackers to induce a Denial of Service (DoS) through the submission of malformed requests. This flaw can potentially lead to stack overflow errors in applications using affected versions before 2.1.1. Users are strongly advised to update to the latest version to apply the necessary security patch, as there are currently no known workarounds to mitigate this issue.

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Affected Version(s)

multer 0 < 2.1.1

References

https://github.com/expressjs/multer/security/advisories/G...
https://www.cve.org/CVERecord?id=CVE-2026-3520
https://github.com/expressjs/multer/commit/7e66481f8b2e6c...

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Yuki Matsuhashi
Chris de Almeida
Ulises GascĂłn
JSON
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